1994 Dodge Ram rough idle when cold

GARDEKUS

MEMBER
1994 DODGE RAM
V8
4WD
AUTOMATIC
212,000 MILES

Ok I changed the trans in my truck, replaced with a used one. Now truck runs really rough till it warms up.
its not so bad when I put it in reverse. After it runs 15-20 min. It will be ok unless I leave it sit for more then 4 hrs. There seems to be some knocking- tapping coming from trans till it gets warn. But then everything seems ok and runs great. I've changed O2,
tps, cap, plugs, wires, roter, egr most anything that would have to do with engine, and im thinking its got to be trans. Could trans oil presure cause a rough idle untill it warms up?

3 Replies

JACOBANDNICKOLAS

MECHANIC
108,133 POSTS

The trans won't cause a rough idle when cold. Has the check engine light come on? Have you checked for vacuum leaks?

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Wednesday, October 6th, 2010 AT 12:41 PM

GARDEKUS

MEMBER
2 POSTS

I've found no vac leaks, it seems to be good everywhere I check. No engine light or codes coming up. Just seems to idle fine when cold if I put it in reverse. Bad when in p, n, and d untill it warms up. Heard someplace that ecm only reads from 3 sensors untill it reaches temp. Just dont know what ones they are. This thing has got me stumped.